1. Field of the Invention
The present invention relates to a piezoelectric/electrostrictive film type device, and a method of manufacturing the device, and more particularly to a piezoelectric/electrostrictive film type device which exhibits superior piezoelectric/electrostrictive characteristics and in which considerations are given to even environments, and a method of manufacturing the device.
2. Description of the Related Art
Heretofore, piezoelectric/electrostrictive devices have been known to be capable of controlling micro-displacement of the order of sub-microns. Especially, a piezoelectric/electrostrictive film type device is preferable for the control of the micro displacement. In the film type device, a piezoelectric/electrostrictive portion constituted of a piezoelectric/electrostrictive composition and an electrode portion to which a voltage is applied are laminated on a substrate made of a ceramic. Additionally, the film type device has superior characteristics such as a high electromechanical conversion efficiency, a high-speed response, a high durability, and a saved power consumption. The piezoelectric/electrostrictive device is used in various applications such as a piezoelectric pressure sensor, a probe moving mechanism of a scanning type tunnel microscope, a rectilinear guide mechanism in an ultra-precise working device, a servo valve for hydraulic control, a head of a VTR device, a pixel constituting a flat panel type image display device, and a head of an ink jet printer
Moreover, the piezoelectric/electrostrictive composition constituting the piezoelectric/electrostrictive portion has also been variously investigated. For example, there has been disclosed a Pb(Mg1/3Nb2/3)O3—PbZrO3—PbTiO3 three-component dissolved composition (PZT-based composition), or a piezoelectric/electrostrictive composition in which a part of Pb in the PZT-based composition is replaced with Sr, La or the like (see, e.g., Patent Documents 1 and 2). As to the piezoelectric/electrostrictive portion itself, which is the most important portion that determines the piezoelectric/electrostrictive characteristics of the piezoelectric/electrostrictive device, there is expected to be obtained the piezoelectric/electrostrictive device having a superior piezoelectric/electrostrictive characteristic (e.g., piezoelectric d constant).
Additionally, the PZT-based composition unavoidably contains lead (Pb). Especially, in recent years, an influence on global environments, such as elution of lead (Pb) due to acid rain, has tended to be regarded as a problem. Therefore, as a piezoelectric/electrostrictive material in which the influence on the environments is considered, there is disclosed a piezoelectric porcelain (or a piezoelectric composition) capable of providing a piezoelectric article or a piezoelectric device which exhibits the satisfactory piezoelectric/electrostrictive characteristic although lead (Pb) is not contained (see, e.g., Patent Documents 3 to 6).
However, as to the piezoelectric article or the like obtained using the piezoelectric porcelain (or the piezoelectric composition) disclosed in Patent Documents 3 to 6, a large displacement is not easily obtained as compared with the piezoelectric article obtained using the PZT-based composition containing lead (Pb). In respect of superiority/inferiority of the piezoelectric/electrostrictive characteristic, it cannot be said that the PZT-based composition is superior in the present situation. Therefore, there has been a necessity for developing a device exhibiting superior piezoelectric/electrostrictive characteristics even in a case where lead (Pb) is not contained.
[Patent Document 1] Japanese Patent Publication No. 44-17106
[Patent Document 2] Japanese Patent Publication No. 45-8145
[Patent Document 3] Japanese Patent Application Laid-Open No. 2003-221276
[Patent Document 4] Japanese Patent Application Laid-Open No. 2003-277145
[Patent Document 5] Japanese Patent Application Laid-Open No. 2002-68836
[Patent Document 6] Japanese Patent Application Laid-Open No. 2004-244299